GIS Data

1
GIS Data

• Engineering Applications of GIS
• Civil and Environmental Engineering
• CEEn 514

2
Definitions

• Data and Information are often used
  interchangeably.
• However, there are some important differences
• Consider the following

3
Data

• Facts, numbers representing facts.
• In its raw form data does not offer meaning, like
  pieces of a puzzle.

4
Information

• Meaning from multiple facts or numbers.
• Putting the pieces of the puzzle together.

5
Data and Information

• A single piece of data could represent
  information.
• By the way data is plural, so it is correct to
  say the data are and not the the data is

6
Data vs Information
Data
Information
7
Spatial Data Characteristics

• Position
• Length, Area, Perimeter
• Connectivity
• Adjacency
• Time???
• Projection (3D, 2D, etc.)

8
Features

• Point datasets

One-to-one relation between features in the map
and records in the table.
9
Features

• Line datasets

One-to-one relation between features in the map
and records in the table.
10
Features

• Polygon datasets

One-to-one relation between features in the map
and records in the table.
11
Surfaces (Rasters)

• Grid datasets

12
Surfaces

• TIN datasets

13
Surfaces

• Image datasets

14
Networks

• Simple dentritic networks

15
Feature Classification

• Categorical Attributes
• Any kind of ID like land use, soils, zoning, etc.
• Quantitative Attributes
• Population, Length, Volume, etc.

16
Categorical Display

• Unique Values
• One or many attributes

17
Quantitative Display

• Graduated Color
• Graduated Symbol
• Proportional Symbol
• Dot Density

18
Classification Methods

• Natural Breaks
• Equal Interval
• Defined Interval
• Quantile
• Std. Deviation
• Manual

19
Labeling

• Tied to Attributes in a table
• Other labels are just text
• Can be dynamic
• Changes size as you zoom, etc.
• Interactive (you decide where to place)
• Annotation
• Converts labels to text